<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .c1{
            background-color: red;
            height: 100px;
            width: 100px;
            float: left;
        }
        .c2{
            background-color: blue;
            height: 100px;
            width: 100px;
            float: right;
        }
        .c3{
            background-color: pink;
            height: 200px;

        }
        .cc{
            /*height: 100px;*/

        }
        .clearfix:after{
            content: '';
            display: block;
            clear: both;
        }


    </style>
</head>
<body>


<div class="cc clearfix">
    <!--<span>xxx</span>-->
    <div class="c1"></div>
    <div class="c2"></div>

</div>

<div class="c3"></div>


</body>
</html>